The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Vehicles include a powertrain that generates drive torque used to propel the vehicle. Typically, the powertrain includes an internal combustion engine and a transmission. The engine produces drive torque by combusting an air and fuel (A/F) mixture within cylinders to drive pistons, which rotate a crankshaft. The transmission transmits drive torque produced by the engine at one or more gear ratios to a driveline, which drives one or more wheels of the vehicle. The transmission includes a gear train including one or more gear sets for transferring torque at various gear ratios.
Torque produced by the engine may also be used to power one or more engine peripherals associated with an electrical system and/or a cooling system of the vehicle. For example, engine torque may be used to power an alternator that produces energy for the electrical system and/or a fluid pump that circulates coolant through the engine. During operation, the engine peripherals generate a load on the engine, which may be referred to as a parasitic load.
Powertrain control systems have been developed to control operation of the engine and transmission, including engine torque output and transmission gear ratio. The powertrain control systems control engine torque output by controlling an amount of air flow into the engine and an amount of fuel provided to the cylinders. During periods of vehicle deceleration such as during vehicle braking, the provision of fuel may be halted to conserve fuel during what may be referred to as a deceleration fuel cutoff (DFCO) period. Some powertrain control systems control transmission gear ratio by controlling fluid pressures supplied to hydraulic actuators used to shift between the various gear ratios of the transmission.